The present invention concerns a novel alarm system and, more particularly, an alarm system which avoids the problems concomitant with alarm systems that are wired to an alarm monitoring station.
It is typical for alarm systems, such as burglar alarm systems, to be connected via telephone lines to an alarm monitoring station. For example, the premises typically have a protective circuit which may comprise a number of intrusion detectors, a voltage source, a sensing relay and wiring connecting these components in series. The alarm system generally includes an alarm control panel where the sensing relay may be located, a key operated switch, and a latching relay. When an alarm condition occurs, the latching relay is caused to activate an audible and/or visible warning device and/or a signal that is transmitted via telephone lines to a police station or central office. In some instances, a dedicated telephone line from the premises to the police station is used. In other instances, a shared telephone line is used and a particular signal is issued on the telephone line corresponding to the alarm condition that has occurred.
An essential link between the protected premises and the police station or central office is the telephone line. However, the telephone wire may be cut and the voltage may be simulated, which will prevent the police station or central office from receiving the alarm communication.
It is, therefore, an object of the present invention to provide an alarm system in which there are no telephone lines connecting the protected premises to a police station or central office.
Another object of the present invention is to provide an alarm system that enables a telephone call to be made to an alarm monitoring station when an alarm condition occurs, without the problems concomitant with a hard wired system.
A further object of the present invention is to provide an alarm system that is reliable in operation, and uses wireless, over-the-air transmission without the restricted number of radio channel frequencies available with conventional mobile telephone systems. One of the serious problems with conventional mobile telephone systems is the restricted number of radio channel frequencies that are available, which may result in a substantial time period before an open line is available. The restricted number of available radio channel frequencies that are available with conventional mobile telephone systems seriously hampers the use of such systems in connection with premises that are protected by an alarm system.
Other objects and advantages of the present invention will become apparent as the description proceeds.